We propose to replace an unrepairable amino acid analyzer and to upgrade a protein sequencer in order to maintain state-of-the-art instrumentation in our Protein Chemistry Facility. Six primary and at least 4 secondary users will utilize the requested instruments in a variety of projects. 1) The relationship of structure to function of nucleolar RNA associated proteins will be studied. 2) The sequences, sites of cofactor attachment and regions of protein-protein interactions of electron carrier proteins will be determined. 3) The functional properties of myelin protein P(O) will be investigated. 4) The structures and roles of posttranslational modifica- tions of eukaryotic protein synthesis initiation and elongation factors will be elucidated. 5) The many structures of fish immunoglobulins will be determined. 6) The amino acid content of newly isolated bacterial siderophores will be analyzed. Additional applications will include quality control of chemically synthesized peptides, accurate protein concentration determinations for biophysical studies, characterization of Chironomus salivary gland secretion polypeptides, partial sequencing of mRNA binding proteins and identification of tRNA binding sites on aminoacyl tRNA synthetases.